Field of the Invention
The present invention relates to devices for controlling automatic operation of a windshield wiper in a motor vehicle and, more particularly, to devices for controlling automatic operation of a windshield wiper with improved control means for adjusting rain sensor sensitivity.
A wiper device with a rain sensor is known on the market. It controls the wiping frequency of a motor vehicle windshield wiper as a function of the rain intensity or the wetting of a front window. This involves for instance optical rain sensors, which couple infrared or visual light from a transmitter into the window at one point, conducted along a measurement path within the window, and at a further point couple it back out of the window again at a receiver. The intensity of the light received by the receiver is dependent on the degree of wetting of the window in the region of the measurement path and is delivered as a sensor signal to an evaluator.
In addition, via a lever on the steering column, the vehicle driver manually turns on the automatic wiping function of the wiper device.
In addition, once again manually, the driver can set the sensitivity of the rain sensor via a knurled wheel on the lever on the steering column.
A disadvantage of this is that setting the sensitivity of the rain sensor via a resistance-encoded switch on the lever on the steering column entails increased effort and expense, because a potentiometer, a tap-changing circuit or a resistance circuit are additionally disposed in the lever on the steering column.